So sorry to hear that… but if the fetal heartbeat is not heard then the pregnancy has stopped. Doctor telling you to scan in another week is to ascertain whether the body will start showing signs of flushing it out naturally or medicine/d&c is needed.
not too sure if the radiologist is skilled enough to detect where the heartbeat is. nonetheless, can only go back for another scan in a week as advised by doctor. please take care meanwhile and all the best to both of you!